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参数资料
| 型号： | LM3102TLX-1 |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PBGA28 |
| 封装： | USMD-28 |
| 文件页数： | 5/20页 |
| 文件大小： | 623K |
| 代理商： | LM3102TLX-1 |
N-Channel MOSFET and Driver
The LM3102 integrates an N-Channel main MOSFET and an
associated floating high voltage main MOSFET gate driver.
The gate drive circuit works in conjunction with an external
bootstrap capacitor C
BST and an internal high voltage diode.
C
BST connecting between the BST and SW pins powers the
main MOSFET gate driver during the main MOSFET on-time.
During each off-time, the voltage of the SW pin falls to ap-
proximately -1V, and C
BST charges from VCC through the
internal diode. The minimum off-time of 260 ns provides
enough time for charging C
BST in each cycle.
Soft-Start
The soft-start feature allows the converter to gradually reach
a steady state operating point, thereby reducing startup
stresses and current surges. Upon turn-on, after V
CC reaches
the under-voltage threshold, an 8 A internal current source
charges up an external capacitor C
SS connecting to the SS
pin. The ramping voltage at the SS pin (and the non-inverting
input of the regulation comparator as well) ramps up the out-
put voltage V
OUT in a controlled manner.
An internal switch grounds the SS pin if any of the following
three cases happens: (i) V
CC is below the under-voltage lock-
out threshold; (ii) a thermal shutdown occurs; or (iii) the EN
pin is grounded. Alternatively, the output voltage can be shut
off by connecting the SS pin to ground using an external
switch. Releasing the switch allows the SS pin to ramp up and
the output voltage to return to normal. The shutdown config-
uration is shown in Figure 3.
30021327
FIGURE 3. Alternate Shutdown Implementation
Thermal Protection
The junction temperature of the LM3102 should not exceed
the maximum limit. Thermal protection is implemented by an
internal Thermal Shutdown circuit, which activates (typically)
at 165°C to make the controller enter a low power reset state
by disabling the main MOSFET, disabling the on-timer, and
grounding the SS pin. Thermal protection helps prevent
catastrophic failures from accidental device overheating.
When the junction temperature falls back below 145°C (typi-
cal hysteresis = 20°C), the SS pin is released and normal
operation resumes.
Thermal Derating
The LM3102 is capable of supplying 2.5A below an ambient
temperature of 100°C. Under worst case operation, with ei-
ther input voltage up to 42V, operating frequency up to 1 MHz,
or voltage of the RON pin below the absolute maximum of 7V,
the LM3102 can deliver a minimum of 1.9A output current
without thermal shutdown with a PCB ground plane copper
area of 40cm2, 2 oz/Cu. Figure 4 shows a thermal derating
curve for the minimum output current without thermal shut-
down against ambient temperature up to 125°C. Obtaining
2.5A output current is possible by increasing the PCB ground
plane area, or reducing the input voltage or operating fre-
quency.
30021340
FIGURE 4. Thermal Derating Curve
13
www.national.com
LM3102
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相关代理商/技术参数 |
参数描述 |
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| LM3102TLX-1/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM3103 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:SIMPLE SWITCHER㈢ Synchronous 1MHz 0.75A Step-Down Voltage Regulator |
| LM3103EVAL | 功能描述:电源管理IC开发工具 LM3103 EVAL BOARD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| LM3103EVAL/NOPB | 功能描述:电源管理IC开发工具 LM3103 EVAL BRD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| LM3103MH | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Down 4.5V to 42V 16-Pin TSSOP EP Tube 制造商:Texas Instruments 功能描述:IC, V REG, SYNCH, 0.75A, POWERWISE |
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